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Regular User

The River Tyburn. One of the Thames' major tributaries, once a large flowing stream, now a bricked over sewer carrying the fetid matter of the London populace away. It's a long tunnel, but only really navigable from St John's Wood onwards, snaking down past Regents Park, underneath Baker Street station and running over Oxford Street towards Mayfair and Green Park. It takes a royal twist under a large stone Palace and then heads straight underneath Victoria and down through Pimlico as it hits the Thames.

Here's a little rough map I put together showing the course of the King's Scholar's Pond (KSP) CSO, and where it interacts with the interceptor system implemented by Sir Joseph Bazalgette in the 1850's.

Ojay and I walked the length of it over 4 or 5 trips, along with many walks topside trying to locate lids and plot the modern-day course of the old river. Other than namesake streets, the only indicators that there's something underground are the breathing vents and manhole lids littering the roads and pavements. Walking alongside it you often pick up the whiff of fresh, teasing your senses and alluring you down.

Our journey begins in St. John's Wood, where the water coming downstream from the source is sent flying down the staircase to the left and into the Mid Level Interceptor 2. From here on in the River Tyburn is gone, with the contents of toilets, washing machine, dishwashers and surface water drains providing the flow.

Behind me in the shot above the tunnel continues. As with downstream of every interceptor chamber the tunnel is dry, before side pipes start emptying in.

We arrive at a chamber where the KSP comes in from the right, with a local sewer coming from the centre pipe. The left hand branch here is bricked up and disused.

The tunnel now opens up and runs down the side of Regent's Park. Not shown in the photo but further along tree roots have breached the tunnel and side pipes, compromising the structural integrity of the sewer and adding an interesting visual.

As we approach Baker Street underground station cast iron reinforcement works have been carried out to ensure the subterranean swiss cheese doesn't collapse on itself.

We're now heading south through the Marylebone area. Lots of small side pipes and local sewers start joining the network, adding more matter to the course.

Seemingly over-engineered cable routing snakes around the tunnel. The sewage network providing valuable real estate for communication companies wanting to lay fibre-optic cables without the expense and inconvenience of closing and digging up roads.

As we approach Oxford street the flow is sent down a large tumbling bay to a lower level. You can just make this out in the distance of the photo below. A roaring beast that appeared suicidal to traverse. The tunnel to the right here takes the flow down to the Mid Level 1 interceptor and away towards Abbey Mills. Final destination is Beckton sewage works out to the East. Being dragged off down there would most certainly be the last thing you ever did.

Another dry post-interceptor tunnel that has had recent reinforcement work. The water in here was stagnant and fairly putrid.

A reverse tumbling bay. The flow would have to be fast and fierce enough to rise above the staircase to carry on further downstream. I could only ever imagine this happening if they closed off the interceptor upstream, but note the debris on the hand rail...

Underneath Bond Street underground station they've had to add cast iron supports and joists to counteract damaged sections. The base of the tunnel has been lined with a thick rubber sheet, presumably to prevent water further damaging the brickwork. There's a large build-up of fat in this section, approximately 18 inches in height.

As we head down through Mayfair the flow starts to build up as more local sewers start rejoining us.

And it all backs up behind this mini weir section. We kicked up some shit walking through this part, which was almost balls deep in filth.

This section onwards was possibly my favourite part. The different construction types and dated tunnels creating a mish-mash of colours and shapes. The workmanship that went into building these places is phenomenal.

As we near Green Park we enter a large overflow chamber. When the water level rises above the weir boards on the left any surplus flow is diverted down into the Ranelagh Storm Relief system. This takes the pressure off the already at capacity interceptor system and prevents some of the filth flowing into the Thames.

We're now underneath Green Park, where there's a row of 4 side entrances that all lead up into the wilderness. Lots of roots and spiders around here.

A short walk further and the flow is directed down a winding tunnel into the Low Level 2 interceptor. This is looking downstream towards the south of Green Park.

The dry tunnel was welcomed at this point, and more evidence of what's above us.

This highly royal section of sewer takes us under the Buckingham Palace estate. A series of bricked up access shafts prevent any would-be idiots entering the grounds, and small side pipes carry in the regal nuggets of anyone inhabiting the Palace.

The sewer gets its name from Westminster school's most ablest pupils. Ironically there's still similar entitlements offered by local universities to the same name, which if they knew earned them the same name right of a sewer they'd perhaps not be so happy about it.

We now enter the area around Victoria station, where the tunnel snakes around.

Before reaching a section that's been recently uncovered amid new foundations being laid for the new ticket hall and extension to the station above. It would have taken too long to apparently lay brick back down, so large sections of concrete unfortunately ruin the ambiance.

A large hydraulic flap sits here, ready to spring into action and scarily close off the next section of tunnel. No one's really sure in what circumstance they do this, so it feels quite sketchy when you walk beneath it.

The newest part of the KSP. A large concrete section with height warning signs.

The flow travels further before hitting a large flap that closes the tunnel off. This one isn't hydraulic, and is permanently closed unless the flow is forceful enough to open it and pass on to the next section. There's a small "cat-flap" at the bottom that allows minimal water to pass through.

Because of the flaps in the area the air circulation is poor. In a couple of sections there are massive build ups of silt under the water. Stepping through it kicked up borderline dangerous levels of Hydrogen Sulphide (H2S) which sits in the tunnel. I was glad to retreat upstream and out of the nearest manhole, that's for sure.

The flap from the other side, where another large side tunnel is being restrained by an iron flap. Again, when the flow rises high enough it will push this open.

The tunnel starts to get higher and wider, with another reinforced section to counter something heavy above. It's not that deep under the surface so unlikely to be tube related, so perhaps a building or major road.

It continues to get larger whilst the flow starts going through a central channel. You can make out tide marks towards the top of the tunnel, showing that this tunnel can, and has, filled right up.

The central channel gains more depth and reminded me of a scene from Ghostbusters 2 for some reason. I think there's more slime here, although thankfully not possessed.

The channel veers off to the left as we approach the outfall tunnel. It's taken off to join the Low Level 1 interceptor, it's final point before reaching the Thames. This helps minimalise the amount of raw sewage that escapes the system and enters the river. Current estimates from Thames Water show that upwards of 39 million tones of sewage spills out annually.

An inspection gallery down above the interceptor. The tunnel drops to an unknown depth from here, and is probably hiding a nasty current.

Heading back into the main tunnel and downstream takes us into a large RCP (Reinforced Concrete Pipe) that fills up with Thames water, silt and sludge during high tide. The tide line here isn't too deep, but the slippy mud-like consistency is awkward to wade through. The closer to the outfall you get, the deeper it goes. The tide was slowly coming back in as we edged towards the final chamber.

The final chamber. The other side of that iron flap is the River Thames. You can make out piles of mud up the side of the brick boxed section that has built up over the years.

Regular User

Despite not usually being the biggest fan of sewer stuff personally (I admire you guys' dedication though!) that was a really interesting write up and some beautiful shots to boot. That brickwork really is stunning.